Comments on: Writing a compiler… http://blog.ngedit.com/2005/05/26/writing-a-compiler/ A blog on the development of the NGEDIT text editor Fri, 30 Jul 2010 00:04:13 +0000 http://wordpress.org/?v=2.3.2 By: J http://blog.ngedit.com/2005/05/26/writing-a-compiler/#comment-6258 J Sun, 17 Sep 2006 21:01:55 +0000 http://blog.ngedit.com/2005/05/26/writing-a-compiler/#comment-6258 Andreas, yeah, it's a long time I haven't touched NGS. Thanks for pointing out a case where the comma actually changes the meaning. Actually, the parentheses are incredibly overused in C-like languages (expression priority, function call, part of specific constructs like if, while, etc...). The semicolon is less tricky, as it's only used at statement level (although with some inconsistencies - the do-while form for example), so I think it's actually the case that it can be ellided more often. But in any case, this was more of a curiosity than anything else. Actually, I wrote a basic vi/vim emulator in the scripting language, which I then ported to C++, and adding the semicolons back was a PITA :) Andreas, yeah, it’s a long time I haven’t touched NGS. Thanks for pointing out a case where the comma actually changes the meaning. Actually, the parentheses are incredibly overused in C-like languages (expression priority, function call, part of specific constructs like if, while, etc…).

The semicolon is less tricky, as it’s only used at statement level (although with some inconsistencies - the do-while form for example), so I think it’s actually the case that it can be ellided more often.

But in any case, this was more of a curiosity than anything else. Actually, I wrote a basic vi/vim emulator in the scripting language, which I then ported to C++, and adding the semicolons back was a PITA :)

]]> By: Andreas http://blog.ngedit.com/2005/05/26/writing-a-compiler/#comment-6206 Andreas Sun, 17 Sep 2006 06:39:46 +0000 http://blog.ngedit.com/2005/05/26/writing-a-compiler/#comment-6206 A bit late...was just stumbling on this. Leaving out operators is a bit dangerous; using a parser generator will point out misconceptions very quickly. Try removing the comma in 'f (a, (b + c) * 2)'... But then there are languages that do not have commas or parentheses in function invocations, but those are designed for that in the expression department. For the semicolon: Up to now I've only seen languages that take an implicit semicolon at the end of a line. And you should need returns in the statements-for-expression. Actually you shouldn't need returns at all at the end of a function. See ruby. A bit late…was just stumbling on this. Leaving out operators is a bit dangerous; using a parser generator will point out misconceptions very quickly. Try removing the comma in ‘f (a, (b + c) * 2)’… But then there are languages that do not have commas or parentheses in function invocations, but those are designed for that in the expression department.

For the semicolon: Up to now I’ve only seen languages that take an implicit semicolon at the end of a line.

And you should need returns in the statements-for-expression. Actually you shouldn’t need returns at all at the end of a function. See ruby.

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